Encapsulation

In programming, we define encapsulation as the bundling of data (attributes) and methods (functions) that operate on the data into a single unit, called a class. It’s a way to protect the data from being modified by external code. It’s a fundamental concept in object-oriented programming.

Python3 provides a way to define private attributes and methods. We use the _ and __ to indicate that an attribute or a method is private. This means that they can only be accessed within the class. The difference between _ and __ is that the former is a convention, while the latter is a language feature and enables name mangling, aka you cannot (almost) access it from outside the class.

How to define encapsulation

class Beam:
    def __init__(self, length=2, width=0.2, height=0.5):
        self._length = length  # we use _ to indicate that this is a private attribute
        self._width = width
        self._height = height
        self.__volume = None  # we use __ to indicate that this is a private attribute

    def __calculate_volume(self):
        self.__volume = self._length * self._width * self._height

    def get_volume(self):
        self.__calculate_volume()
        return self.__volume

How to use encapsulation

beam = Beam()
print(beam.get_volume())  # 0.2

# not reccomended, but still possible
beam._length = 3
print(beam.get_volume())  # 0.3

# not recommended, and not possible
beam.__volume = 10  # AttributeError: 'Beam' object has no attribute '__volume'

⚠️⚠️⚠️Note that we can still access the private attributes and methods (_), but it’s not recommended. We should use the public methods to access the private attributes and methods.⚠️⚠️⚠️